System for joining building panels

ABSTRACT

The invention relates to a system for laying and mechanically joining building panels, especially thin, hard, floating floors. Adjacent joint edges of two panels engage each other to provide a first mechanical connection locking the joint edges in a first direction perpendicular to the principal plane of the panels. In each joint, there is further provided a strip which is integrated with one joint edge and which projects behind the other joint edge. The strip has an upwardly protruding locking element engaging in a locking groove in the rear side of the other joint edge to form a second mechanical connection locking the panels in a second direction parallel to the principal plane of the panels and at right angles to the joint. Both the first and the second mechanical connection allow mutual displacement of joined panels in the direction of the joint.

TECHNICAL FIELD

[0001] The invention generally relates to a system for providing a jointalong adjacent joint edges of two building panels, especially floorpanels.

[0002] More specifically, the joint is of the type where the adjacentjoint edges together form a first mechanical connection locking thejoint edges to each other in a first direction at right angles to theprincipal plane of the panels, and where a locking device forms a secondmechanical connection locking the panels to each other in a seconddirection parallel to the principal plane and at right angles to thejoint edges, the locking device comprising a locking groove whichextends parallel to and spaced from the joint edge of one of the panels,and said locking groove being open at the rear side of this one panel.

[0003] The invention is especially well suited for use in joining floorpanels, especially thin laminated floors. Thus, the followingdescription of the prior art and of the objects and features of theinvention will be focused on-this field of use. It should however beemphasised that the invention is useful also for joining ordinary woodenfloors as well as other types of building panels, such as wall panelsand roof slabs.

BACKGROUND OF THE INVENTION

[0004] A joint of the aforementioned type is known e.g. from SE 450,141.The first mechanical connection is achieved by means of joint edgeshaving tongues and grooves. The locking device for the second mechanicalconnection comprises two oblique locking grooves, one in the rear sideof each panel, and a plurality of spaced-apart spring clips which aredistributed along the joint and the legs of which are pressed into thegrooves, and which are biased so as to tightly clamp the floor panelstogether. Such a joining technique is especially useful for joiningthick floor panels to form surfaces of a considerable expanse.

[0005] Thin floor panels of a thickness of about 7-10 mm, especiallylaminated floors, have in a short time taken a substantial share of themarket. All thin floor panels employed are laid as “floating floors”without being attached to the supporting structure. As a rule, thedimension of the floor panels is 200×1200 mm, and their long and shortsides are formed with tongues and grooves. Traditionally, the floor isassembled by applying glue in the groove and forcing the floor panelstogether. The tongue is then glued in the groove of the other panel. Asa rule, a laminated floor consists of an upper decorative wear layer oflaminate having a thickness of about 1 mm, an intermediate core ofparticle board or other board, and a base layer to balance theconstruction. The core has essentially poorer properties than thelaminate, e.g. in respect of hardness and water resistance, but it isnonetheless needed primarily for providing a groove and tongue forassemblage. This means that the overall thickness must be at least about7 mm. These known laminated floors using glued tongue-and-groove jointshowever suffer from several inconveniences.

[0006] First, the requirement of an overall thickness of at least about7 mm entails an undesirable restraint in connection with the laying ofthe floor, since it is easier to cope with low thresholds when usingthin floor panels, and doors must often be adjusted in height to comeclear of the floor laid. Moreover, manufacturing costs are directlylinked with the consumption of material.

[0007] Second, the core must be made of moisture-absorbent material topermit using water-based glues when laying the floor. Therefore, it isnot possible to make the floors thinner using so-called compactlaminate, because of the absence of suitable gluing methods for suchnon-moisture-absorbent core materials.

[0008] Third, since the laminate layer of the laminated floors is highlywear-resistant, tool wear is a major problem when working the surface inconnection with the formation of the tongue.

[0009] Fourth, the strength of the joint, based on a gluedtongue-and-groove connection, is restricted by the properties of thecore and of the glue as well as by the depth and height of the groove.The laying quality is entirely dependent on the gluing. In the event ofpoor gluing, the joint will open as a result of the tensile stresseswhich occur e.g. in connection with a change in air humidity.

[0010] Fifth, laying a floor with glued tongue-and-groove joints istime-consuming, in that glue must be applied to every panel on both thelong and short sides thereof.

[0011] Sixth, it is not possible to disassemble a glued floor once laid,without having to break up the joints. Floor panels that have been takenup cannot therefore be used again. This is a drawback particularly inrental houses where the flat concerned must be put back into the initialstate of occupancy. Nor can damaged or worn-out panels be replacedwithout extensive efforts, which would be particularly desirable onpublic premises and other areas where parts of the floor are subjectedto great wear.

[0012] Seventh, known laminated floors are not suited for such use asinvolves a considerable risk of moisture penetrating down into themoisture-sensitive core.

[0013] Eighth, present-day hard, floating floors require, prior tolaying the floor panels on hard subfloors, the laying of a separateunderlay of floor board, felt, foam or the like, which is to damp impactsounds and to make the floor more pleasant to walk on. The placement ofthe underlay is a complicated operation, since the underlay must beplaced in edge-to-edge fashion. Different under-lays affect theproperties of the floor.

[0014] There is thus a strongly-felt need to overcome theabove-mentioned drawbacks of the prior art. It is however not possiblesimply to use the known joining technique with glued tongues and groovesfor very thin floors, e.g. with floor thicknesses of about 3 mm, since ajoint based on a tongue-and-groove connection would not be sufficientlystrong and practically impossible to produce for such thin floors. Norare any other known joining techniques usable for such thin floors.Another reason why the making of thin floors from e.g. compact laminateinvolves problems is the thickness tolerances of the panels, being about0.2-0.3 mm for a panel thickness of about 3 mm. A 3-mm compact laminatepanel having such a thickness tolerance would have, if ground to uniformthickness on its rear side, an unsymmetrical design, entailing the riskof bulging. Moreover, if the panels have different thicknesses, thisalso means that the joint will be subjected to excessive load.

[0015] Nor is it possible to overcome the above-mentioned problems byusing double-adhesive tape or the like on the undersides of the panels,since such a connection catches directly and does not allow forsubsequent adjustment of the panels as is the case with ordinary gluing.

[0016] Using U-shaped clips of the type disclosed in the above-mentionedSE 450,141, or similar techniques, to overcome the drawbacks discussedabove is no viable alternative either. Especially, biased clips of thistype cannot be used for joining panels of such a small thickness as 3mm. Normally, it is not possible to disassemble the floor panels withouthaving access to their undersides. This known technology relying onclips suffers from the additional drawbacks:

[0017] Subsequent adjustment of the panels in their longitudinaldirection is a complicated operation in connection with laying, sincethe clips urge the panels tightly against each other.

[0018] Floor laying using clips is time-consuming.

[0019] This technique is usable only in those cases where the floorpanels are resting on underlying joists with the clips placedtherebetween. For thin floors to be laid on a continuous, flatsupporting structure, such clips cannot be used.

[0020] The floor panels can be joined together only at their long sides.No clip connection is provided on the short sides.

TECHNICAL PROBLEMS AND OBJECTS OF THE INVENTION

[0021] A main object of the invention therefore is to provide a systemfor joining together building panels, especially floor panels for hard,floating floors, which allows using floor panels of a smaller overallthickness than present-day floor panels.

[0022] A particular object of the invention is to provide apanel-joining system which

[0023] makes it possible in a simple, cheap and rational way to providea joint between floor panels without requiring the use of glue,especially a joint based primarily only on mechanical connectionsbetween the panels;

[0024] can be used for joining floor panels which have a smallerthickness than present-day laminated floors and which have, because ofthe use of a different core material, superior properties thanpresent-day floors even at a thickness of 3 mm;

[0025] makes it possible between thin floor panels to provide a jointthat eliminates any unevennesses in the joint because of thicknesstolerances of the panels;

[0026] allows joining all the edges of the panels;

[0027] reduces tool wear when manufacturing floor panels with hardsurface layers;

[0028] allows repeated disassembly and reassembly of a floor previouslylaid, without causing damage to the panels, while ensuring high layingquality;

[0029] makes it possible to provide moisture-proof floors;

[0030] makes it possible to obviate the need of accurate, separateplacement of an underlay before laying the floor panels; and

[0031] considerably cuts the time for joining the panels.

[0032] These and other objects of the invention are achieved by means ofa panel-joining system having the features recited in the appendedclaims.

[0033] Thus, the invention provides a system for making a joint alongadjacent joint edges of two building panels, especially floor panels, inwhich joint:

[0034] the adjacent joint edges together form a first mechanicalconnection locking the joint edges to each other in a first direction atright angles to the principal plane of the panels, and

[0035] a locking device arranged on the rear side of the panels forms asecond mechanical connection locking the panels to each other in asecond direction parallel to the principal plane and at right angles tothe joint edges, said locking device comprising a locking groove whichextends parallel to and spaced from the joint edge of one of saidpanels, termed groove panel, and which is open at the rear side of thegroove panel, said system being characterised in

[0036] that the locking device further comprises a strip integrated withthe other of said panels, termed strip panel, said strip extendingthroughout substantially the entire length of the joint edge of thestrip panel and being provided with a locking element projecting fromthe strip, such that when the panels are joined together, the stripprojects on the rear side of the groove panel with its locking elementreceived in the locking groove of the groove panel,

[0037] that the panels, when joined together, can occupy a relativeposition in said second direction where a play exists between thelocking groove and a locking surface on the locking element that isfacing the joint edges and is operative in said second mechanicalconnection,

[0038] that the first and the second mechanical connection both allowmutual displacement of the panels in the direction of the joint edges,and

[0039] that the second mechanical connection is so conceived as to allowthe locking element to leave the locking groove if the groove panel isturned about its joint edge angularly away from the strip.

[0040] The term “rear side” as used above should be considered tocomprise any side of the panel located behind/underneath the front sideof the panel. The opening plane of the locking groove of the groovepanel can thus be located at a distance from the rear surface of thepanel resting on the supporting structure. Moreover, the strip, which inthe invention extends throughout substantially the entire length of thejoint edge of the strip panel, should be considered to encompass boththe case where the strip is a continuous, uninterrupted element, and thecase where the “strip” consists in its longitudinal direction of severalparts, together covering the main portion of the joint edge.

[0041] It should also be noted (i) that it is the first and the secondmechanical connection as such that permit mutual displacement of thepanels in the direction of the joint edges, and that (ii) it is thesecond mechanical connection as such that permits the locking element toleave the locking groove if the groove panel is turned about its jointedge angularly away from the strip. Within the scope of the invention,there may thus exist means, such as glue and mechanical devices, thatcan counteract or prevent such displacement and/or upward angling.

[0042] The system according to the invention makes it possible toprovide concealed, precise locking of both the short and long sides ofthe panels in hard, thin floors. The floor panels can be quickly andconveniently disassembled in the reverse order of laying without anyrisk of damage to the panels, ensuring at the same time a high layingquality. The panels can be assembled and disassembled much faster thanin present-day systems, and any damaged or worn-out panels can bereplaced by taking up and re-laying parts of the floor.

[0043] According to an especially preferred embodiment of the invention,a system is provided which permits precise joining of thin floor panelshaving, for example, a thickness of the order of 3 mm and which at thesame time provides a tolerance-independent smooth top face at the joint.To this end, the strip is mounted in an equalising groove which iscountersunk in the rear side of the strip panel and which exhibits anexact, predetermined distance from its bottom to the front side of thestrip panel. The part of the strip projecting behind the groove panelengages a corresponding equalising groove, which is countersunk in therear side of the groove panel and which exhibits the same exact,predetermined distance from its bottom to the front side of the groovepanel. The thickness of the strip then is at least so great that therear side of the strip is flush with, and preferably projects slightlybelow the rear side of the panels. In this embodiment, the panels willalways rest, in the joint, with their equalising grooves on a strip.This levels out the tolerance and imparts the necessary strength to thejoint. The strip transmits horizontal and upwardly-directed forces tothe panels and downwardly-directed forces to the existing subfloor.

[0044] Preferably, the strip may consist of a material which isflexible, resilient and strong, and can be sawn. A preferred stripmaterial is sheet aluminium. In an aluminium strip, sufficient strengthcan be achieved with a strip thickness of the order of 0.5 mm.

[0045] In order to permit taking up previously laid, joined floor panelsin a simple way, a preferred embodiment of the invention ischaracterised in that when the groove panel is pressed against the strippanel in the second direction and is turned anglularly away from thestrip, the maximum distance between the axis of rotation of the groovepanel and the locking surface of the locking groove closest to the jointedges is such that the locking element can leave the locking groovewithout contacting the locking surface of the locking groove. Such adisassembly can be achieved even if the aforementioned play between thelocking groove and the locking surface is not greater than 0.2 mm.

[0046] According to the invention, the locking surface of the lockingelement is able to provide a sufficient locking function even with verysmall heights of the locking surface. Efficient locking of 3-mm floorpanels can be achieved with a locking surface that is as low as 2 mm.Even a 0.5-mm-high locking surface may provide sufficient locking. Theterm “locking surface” as used herein relates to the part of the lockingelement engaging the locking groove to form the second mechanicalconnection.

[0047] For optimal function of the invention, the strip and the lockingelement should be formed on the strip panel with high precision.Especially, the locking surface of the locking element should be locatedat an exact distance from the joint edge of the strip panel.Furthermore, the extent of the engagement in the floor panels should beminimised, since it reduces the floor strength.

[0048] By known manufacturing methods, it is possible to produce a stripwith a locking pin, for example by extruding aluminium or plastics intoa suitable section, which is thereafter glued to the floor panel or isinserted in special grooves. These and all other traditional methods dohowever not ensure optimum function and an optimum level of economy. Toproduce the joint system according to the invention, the strip issuitably formed from sheet aluminium, and is mechanically fixed to thestrip panel.

[0049] The laying of the panels can be performed by first placing thestrip panel on the subfloor and then moving the groove panel with itslong side up to the long side of the strip panel, at an angle betweenthe principal plane of the groove panel and the subfloor. When the jointedges have been brought into engagement with each other to form thefirst mechanical connection, the groove panel is angled down so as toaccommodate the locking element in the locking groove.

[0050] Laying can also be performed by first placing both the strippanel and the groove panel flat on the subfloor and then joining thepanels parallel to their principal planes while bending the stripdownwards until the locking element snaps up into the locking groove.This laying technique enables in particular mechanical locking of boththe short and long sides of the floor panels. For example, the longsides can be joined together by using the first laying technique withdownward angling of the groove panel, while the short sides aresubsequently joined together by displacing the groove panel in itslongitudinal direction until its short side is pressed on and locked tothe short side of an adjacent panel in the same row.

[0051] In connection with their manufacture, the floor D panels can beprovided with an underlay of e.g. floor board, foam or felt. Theunderlay should preferably cover the strip such that the joint betweenthe underlays is offset in relation to the joint between the floorpanels.

[0052] The above and other features and advantages of the invention willappear from the appended claims and the following description ofembodiments of the invention.

[0053] The invention will now be described in more detail hereinbelowwith reference to the accompanying drawing Figures.

DESCRIPTION OF DRAWING FIGURES

[0054]FIGS. 1a and 1 b schematically show in two stages how two floorpanels of different thickness are joined together in floating fashionaccording to a first embodiment of the invention.

[0055]FIGS. 2a-c show in three stages a method for mechanically joiningtwo floor panels according to a second embodiment of the invention.

[0056]FIGS. 3a-c show in three stages another method for mechanicallyjoining the floor panels of FIGS. 2a-c.

[0057]FIGS. 4a and 4 b show a floor panel according to FIGS. 2a-c asseen from below and from above, respectively.

[0058]FIG. 5 illustrates in perspective a method for laying and joiningfloor panels according to a third embodiment of the invention.

[0059]FIG. 6 shows in perspective and from below a first variant formounting a strip on a floor panel.

[0060]FIG. 7 shows in section a second variant for mounting a strip on afloor panel.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0061]FIGS. 1a and 1 b, to which reference is now made, illustrate afirst floor panel 1, hereinafter termed strip panel, and a second floorpanel 2, hereinafter termed groove panel. The terms “strip panel” and“groove panel” are merely intended to facilitate the description of theinvention, the panels 1, 2 normally being identical in practice. Thepanels 1 and 2 may be made from compact laminate and may have athickness of about 3 mm with a thickness tolerance of about +0.2 mm.Considering this thickness tolerance, the panels 1, 2 are illustratedwith different thicknesses (FIG. 1b), the strip panel 1 having a maximumthickness (3.2 mm) and the groove panel 2 having a minimum thickness(2.8 mm).

[0062] To enable mechanical joining of the panels 1, 2 at opposing jointedges, generally designated 3 and 4, respectively, the panels areprovided with grooves and strips as described in the following.

[0063] Reference is now made primarily to FIGS. 1a and 1 b, and secondlyto FIGS. 4a and 4 b showing the basic design of the floor panels frombelow and from above, respectively.

[0064] From the joint edge 3 of the strip panel 1, i.e. the one longside, projects horizontally a flat strip 6 mounted at the factory on theunderside of the strip panel 1 and extending throughout the entire jointedge 3. 15 The strip 6, which is made of flexible, resilient sheetaluminium, can be fixed mechanically, by means of glue or in any othersuitable way. In FIGS. 1a and 1 b, the strip 6 is glued, while in FIGS.4a and 4 b it is mounted by means of a mechanical connection, which willbe described in more detail hereinbelow.

[0065] Other strip materials can be used, such as sheets of othermetals, as well as aluminium or plastics sections. Alternatively, thestrip 6 may be integrally formed with the strip panel 1. At any rate,the strip 6 should be integrated with the strip panel 1, i.e. it shouldnot be mounted on the strip panel 1 in connection with laying. As anon-restrictive example, the strip 6 may have a width of about 30 mm anda thickness of about 0.5 mm.

[0066] As appears from FIGS. 4a and 4 b, a similar, although o shorterstrip 6′ is provided also at one short side 3′ of the strip panel 1. Theshorter strip 6′ does however not extend throughout the entire shortside 3′ but is otherwise identical with the strip 6 and, therefore, isnot described in more detail here.

[0067] The edge of the strip 6 facing away from the joint edge 3 isformed with a locking element 8 extended throughout the entire strip 6.The locking element 8 has a locking surface 10 facing the joint edge 3and having a height of e.g. 0.5 mm. The locking element 8 is so designedthat when the floor is being laid and the strip panel 2 of FIG. 1a ispressed with its joint edge 4 against the joint edge 3 of the strippanel 1 and is angled down against the subfloor 12 according to FIG. 1b,it enters a locking groove 14 formed in the underside 16 of the groovepanel 2 and extending parallel to and spaced from the joint edge 4. InFIG. 1b, the locking element 8 and the locking groove 14 together form amechanical connection locking the panels 1, 2 to each other in thedirection designated D2. More specifically, the locking surface 10 ofthe locking element 8 serves as a stop with respect to the surface ofthe locking groove 14 closest to the joint edge 4.

[0068] When the panels 1 and 2 are joined together, they can howeveroccupy such a relative position in the direction D2 that there is asmall play A between the locking surface 10 and the locking groove 14.This mechanical connection in the direction D2 allows mutualdisplacement of the panels 1, 2 in the direction of the joint, whichconsiderably facilitates the laying and enables joining together theshort sides by snap action.

[0069] As appears from FIGS. 4a and 4 b, each panel in the system has astrip 6 at one long side 3 and a locking groove 14 at the other longside 4, as well as a strip 6′ at one short side 3′ and a locking groove14′ at the other short side 4′.

[0070] Furthermore, the joint edge 3 of the strip panel 1 has in itsunderside 18 a recess 20 extending throughout the entire joint edge 3and forming together with the upper face 22 of the strip 6 a laterallyopen recess 24. The joint edge 4 of the groove panel 2 has in its topside 26 a corresponding recess 28 forming a locking tongue 30 to beaccommodated in the recess 24 so as to form a mechanical connectionlocking the joint edges 3, 4 to each other in the direction designatedD1. This connection can be achieved with other designs of the jointedges 3, 4, for example by a bevel thereof such that the joint edge 4 ofthe groove panel 2 passes obliquely in underneath the joint edge 3 ofthe strip panel 1 to be locked between that edge and the strip 6.

[0071] The panels 1, 2 can be taken up in the reverse order of layingwithout causing any damage to the joint, and be laid again.

[0072] The strip 6 is mounted in a tolerance-equalising groove 40 in theunderside 18 of the strip panel 1 adjacent the joint edge 3. In thisembodiment, the width of the equalising groove 40 is approximately equalto half the width of the strip 6, i.e. about 15 mm. By means of theequalising groove 40, it is ensured that there will always exist betweenthe top side 21 of the panel 1 and the bottom of the groove 40 an exact,predetermined distance E which is slightly smaller than the minimumthickness (2.8 mm) of the floor panels 1, 2. The groove panel 2 has acorresponding tolerance-equalising surface or groove 42 in the underside16 of the joint edge 4. The distance between the equalising surface 42and the top side 26 of the groove panel 2 is equal to the aforementionedexact distance E. Further, the thickness of the strip 6 is so chosenthat the underside 44 of the strip is situated slightly below theundersides 18 and 16 of the floor panels 1 and 2, respectively. In thismanner, the entire joint will rest on the strip 6, and all verticaldownwardly-directed forces will be efficiently transmitted to thesubfloor 12 without any stresses being exerted on the joint edges 3, 4.Thanks to the provision of the equalising grooves 40, 42, an entirelyeven joint will be achieved on the top side, despite the thicknesstolerances of the panels 1, 2, without having to perform any grinding orthe like across the whole panels. Especially, this obviates the risk ofdamage to the bottom layer of the compact laminate, which might giverise to bulging of the panels.

[0073] Reference is now made to the embodiment of FIGS. 2a-c showing ina succession substantially the same laying method as in FIGS. 1a and 1b. The embodiment of FIGS. 2a-c primarily differs from the embodiment ofFIGS. 1a and 1 b in that the strip 6 is mounted on the strip panel 1 bymeans of a mechanical connection instead of glue. To provide thismechanical connection, illustrated in more detail in FIG. 6, a groove 50is provided in the underside 18 of the strip panel 1 at a distance fromthe recess 24. The groove 50 may be formed either as a continuous grooveextending throughout the entire length of the panel 1, or as a number ofseparate grooves. The groove 50 defines, together with the recess 24, adovetail gripping edge 52, the underside of which exhibits an exactequalising distance E to the top side 21 of the strip panel 1. Thealuminium strip 6 has a number of punched and bent tongues 54, as wellas one or more lips 56 which are bent round opposite sides of thegripping edge 52 in clamping engagement therewith. This connection isshown in detail from below in the perspective view of FIG. 6.

[0074] Alternatively, a mechanical connection between the strip 6 andthe strip panel 1 can be provided as illustrated in FIG. 7 showing insection a cut-away part of the strip panel 1 turned upside down. In FIG.7, the mechanical connection comprises a dovetail recess 58 in theunderside 18 of the strip panel 1, as well as tongues/lips 60 punchedand bent from the strip 6 and clamping against opposing inner sides ofthe recess 58.

[0075] The embodiment of FIGS. 2a-c is further characterised in that thelocking element 8 of the strip 6 is designed as a component bent fromthe aluminium sheet and having an operative locking surface 10 extendingat right angles up from the front side 22 of the strip 6 through aheight of e.g. 0.5 mm, and a rounded guide surface 34 facilitating theinsertion of the locking element 8 into the locking groove 14 whenangling down the groove panel 2 towards the subfloor 12 (FIG. 2b), aswell as a portion 36 which is inclined towards the subfloor 12 and whichis not operative in the laying method illustrated in FIGS. 2a-c.

[0076] Further, it can be seen from FIGS. 2a-c that the joint edge 3 ofthe strip panel 1 has a lower bevel 70 which cooperates during layingwith a corresponding upper bevel 72 of the joint edge 4 of the groovepanel 2, such that the panels 1 and 2 are forced to move verticallytowards each other when their joint edges 3, 4 are moved up to eachother and the panels are pressed together horizontally.

[0077] Preferably, the locking surface 10 is so located relative to thejoint edge 3 that when the groove panel 2, starting from the joinedposition in FIG. 2c, is pressed horizontally in the direction D2 againstthe strip panel 1 and is turned angularly up from the strip 6, themaximum-distance between the axis of rotation A of the groove panel 2and the locking surface 10 of the locking groove is such that thelocking element 8 can leave the locking groove 14 without coming intocontact with it.

[0078]FIGS. 3a-3 b show another joining method for mechanically joiningtogether the floor panels of FIGS. 2a-c. The method illustrated in FIGS.3a-c relies on the fact that the strip 6 is resilient and is especiallyuseful for joining together the short sides of floor panels which havealready been joined along one long side as illustrated in FIGS. 2a-c.The method of FIGS. 3a-c is performed by first placing the two panels 1and 2 flat on the subfloor 12 and then moving them horizontally towardseach other according to FIG. 3b. The inclined portion 36 of the lockingelement 8 then serves as a guide surface which guides the joint edge 4of the groove panel 2 up on to the upper side 22 of the strip 6. Thestrip 6 will then be urged downwards while the locking element 8 issliding on the equalising surface 42. When the joint edges 3, 4 havebeen brought into complete engagement with each other horizontally, thelocking element 8 will snap into the locking groove 14 (FIG. 3c),thereby providing the same locking as in FIG. 2c. The same lockingmethod can also be used by placing, in the initial position, the jointedge 4 of the groove panel with the equalising groove 42 on the lockingelement 10 (FIG. 3a). The inclined portion 36 of the locking element 10then is not operative. This technique thus makes it possible to lock thefloor panels mechanically in all directions, and by repeating the layingoperations the whole floor can be laid without using any glue.

[0079] The invention is not restricted to the preferred embodimentsdescribed above and illustrated in the drawings, but several variantsand modifications thereof are conceivable within the scope of theappended claims. The strip 6 can be divided into small sections coveringthe major part of the joint length. Further, the thickness of the strip6 may vary throughout its width. All strips, locking grooves, lockingelements and recesses are so dimensioned as to enable laying the floorpanels with flat top sides in a manner to rest on the strip 6 in thejoint. If the floor panels consist of compact laminate and if siliconeor any other sealing compound, a rubber strip or any other sealingdevice is applied prior to laying between the flat projecting part ofthe strip 6 and the groove panel 2 and/or in the recess 26, amoisture-proof floor is obtained.

[0080] As appears from FIG. 6, an underlay 46, e.g. of floor board, foamor felt, can be mounted on the underside of the panels during themanufacture thereof. In one embodiment, the underlay 46 covers the strip6 up to the locking element 8, such that the joint between the underlays46 becomes offset in relation to the joint between the joint edges 3 and4.

[0081] In the embodiment of FIG. 5, the strip 6 and its locking element8 are integrally formed with the strip panel 1, the projecting part ofthe strip 6 thus forming an extension of the lower part of the jointedge 3. The locking function is the same as in the embodiments describedabove. On the underside 18 of the strip panel 1, there is provided aseparate strip, band or the like 74 extending throughout the entirelength of the joint and having, in this embodiment, a width coveringapproximately the same surface as the separate strip 6 of the previousembodiments. The strip 74 can be provided directly on the rear side 18or in a recess formed therein (not shown), so that the distance from thefront side 21, 26 of the floor to the rear side 76, including thethickness of the strip 74, always is at least equal to the correspondingdistance in the panel having the greatest thickness tolerance. Thepanels 1, 2 will then rest, in the joint, on the strip 74 or only on theundersides 18, 16 of the panels, if these sides are made plane.

[0082] When using a material which does not permit downward bending ofthe strip 6 or the locking element 8, laying 20 can be performed in theway shown in FIG. 5. A floor panel 2 a is moved angled upwardly with itslong side 4 a into engagement with the long side 3 of a previously laidfloor panel 1 while at the same time a third floor panel 2 b is movedwith its short side 4 b′ into engagement with the short side 3 a′ of theupwardly-angled floor panel 2 a and is fastened by angling the panel 2 bdownwards. The panel 2 b is then pushed along the short side 3 a′ of theupwardly-angled floor panel 2 a until its long side 4 b encounters thelong side 3 of the initially-laid panel 1. The two upwardly-angledpanels 2 a and 2 b are therefore angled down on to the subfloor 12 so asto bring about locking.

[0083] By a reverse procedure the panels can be taken up in the reverseorder of laying without causing any damage to the joint, and be laidagain.

[0084] Several variants of preferred laying methods are conceivable. Forexample, the strip panel can be inserted under the groove panel, thusenabling the laying of panels in all four directions with respect to theinitial position.

What is claimed is:
 1. A mechanical locking system for locking a firstedge of a first panel to a second edge of an identical second panel thatare arranged on a subfloor, the mechanical locking system comprising: aconnector system on the first edge and the second edge for forming afirst mechanical connection locking the first and second edges to eachother in a first direction at right angles to a principal plane of thepanels; and a locking device arranged on an underside of the first andthe second edges, the locking device forming a second mechanicalconnection locking the first and the second edges to each other in asecond direction parallel to the principal plane and at right angles tothe edges, wherein the connector system includes a tongue and a groove,the groove being defined, in part, by a strip that is made in one piecewith the first edge of the first panel and the tongue being made in onepiece with the second edge of the second panel, a thickness of the stripvaries as the strip extends from the first panel, an inner part of thetongue adjacent the second panel being thicker than a distal, outer partof the tongue, wherein the tongue and the groove are configured suchthat, when the first and second edges are joined together, a spaceexists between an inner part of the groove and the distal, outer part ofthe tongue, and wherein the tongue and the groove are configured suchthat when the second edge is pressed against an upper part of the firstedge and is then angled down against the subfloor, the tongue can enterthe groove to effect the first and second mechanical connections.
 2. Themechanical locking system as claimed in claim 1, wherein the groove iswider at an outer part than at an inner part.
 3. The mechanical lockingsystem as claimed in claim 1, further comprising an upper lip extendingfrom the first edge of the first panel to further define the groove,wherein an outer part of the upper lip is thinner than an inner part ofthe upper lip.
 4. The mechanical locking system as claimed in claim 3,wherein the upper lip includes a first contact surface for contacting asecond contact surface on the tongue, wherein the first contact surfaceand the second contact surface are substantially parallel with theprincipal plane.
 5. A mechanical locking system for locking a first edgeof a first panel to a second edge of a second panel, the mechanicallocking system comprising: a tongue and groove on the first edge and thesecond edge for forming a first mechanical connection locking the firstand second edges to each other in a first direction at right angles to aprincipal plane of the panels; and a locking device arranged on anunderside of the first and the second edges, the locking device forminga second mechanical connection locking the first and the second edges toeach other in a second direction parallel to the principal plane and atright angles to the edges, wherein the groove is defined, in part, by astrip that is made in one piece with the first edge of the first panel,wherein the tongue is made in one piece with the second edge of thesecond panel, wherein a thickness of the strip varies as the stripextends from the first panel, wherein an inner part of the tongueadjacent the second panel is thicker than a distal, outer part of thetongue, wherein the tongue and groove are configured such that, when thefirst and second edges are joined together, a space exists between aninner part of the groove and the distal, outer part of the tongue, andwherein the tongue and groove are configured such that when the secondedge is pressed against an upper part of the first edge and is thenangled down, the tongue can enter the groove to effect the first andsecond mechanical connections.
 6. A mechanical locking system forlocking a first edge of a first panel to a second edge of a second panelso that the first and second panels form a joint plane, the mechanicallocking system comprising: a tongue on the first edge; and a groove onthe second edge wherein the tongue and the groove form a mechanicalconnection locking the first edge and the second edge to each other in afirst direction at right angles to a principal plane of the panels,wherein the groove has a lower surface that is defined, at least inpart, by a strip that extends from the second edge of the second panelsuch that a distal end of the strip extends beyond the joint plane,wherein the tongue is made in one piece with the first panel andprojecting beyond the joint plane, wherein the tongue and the groove areconfigured such that, when the first edge and the second edge are joinedtogether, a space exists between an inner part of the groove and thedistal, outer part of the tongue, wherein the strip is substantiallycoplanar with a bottom surface of the second panel, and wherein thetongue and groove are configured such that when the second edge ispressed against an upper part of the first edge and is then angled down,the tongue can enter the groove to effect the mechanical connection, thefirst panel and the second panel configured so as to enable the panelsto be separated by angling the first panel and the second panel withrespect to each other.
 7. The mechanical locking system of claim 6,wherein the first panel and second panel form a laminated floor.
 8. Themechanical locking system of claim 6, wherein: a thickness of the stripvaries as the strip extends from the first panel; an inner part of thetongue adjacent the second panel being thicker than a distal, outer partof the tongue.
 9. A floating laminate floor panel comprising a pluralityof floor boards, wherein each floor board includes an upper decorativewear layer, a core layer arranged beneath the upper decorative wearlayer, the core layer being made of a material that is not as hard asthe upper decorative wear layer, a base layer beneath the core layer,and a mechanical locking system for locking a first edge of a firstfloor board to a second edge of a second floor board, the mechanicallocking system comprising: a tongue on the first edge and a groove onthe second edge forming a first mechanical connection locking the firstand second edges to each other in a first direction at right angles to aprincipal plane of the floor boards, the tongue and groove being formedin the material of the core layer; and a locking device arranged on anunderside of the first and the second edges, the locking device forminga second mechanical connection locking the first and the second edges toeach other in a second direction parallel to the principal plane and atright angles to the edges, wherein the locking device includes a lockinggroove which extends parallel to and spaced from the second edge, thelocking groove being open at the underside of the second edge andincluding an internal surface, wherein the locking device furtherincludes a strip extending from the first edge, the strip extendingthroughout substantially an entire length of the first edge and beingprovided with a locking element projecting from the strip, wherein thestrip, the locking element, and the locking groove are configured suchthat when the second edge is pressed against an upper part of the firstedge and is then angled down, the locking element can enter the lockinggroove, and wherein the locking element has a locking surface whichfaces the first edge and is configured so as to contact the internalsurface of the locking groove to prevent substantial separation of thejoined first edge and second edge.
 10. The floating laminate floor boardof claim 9, wherein the core layer is made of particle board.
 11. Thefloating laminate floor board of claim 9, wherein the board is equal toor less than 10 mm in thickness.
 12. The floating laminate floor boardof claim 11, wherein the locking element has a locking surface with aheight of about 0.5 to 2 mm.
 13. The floating laminate floor board ofclaim 9, wherein the core layer is made from particle board or otherboard material.
 14. The floating laminate floor board of claim 9,wherein the locking element has a locking surface with a height of about0.5 to 2 mm.
 15. A floor panel comprising: an upper decorative wearlayer; a core layer arranged beneath the upper decorative wear layer,the core layer being made of a material that is not as hard as the upperdecorative wear layer; a base layer beneath the core layer; and amechanical locking system for locking a first edge of a first floorboard to a second edge of a second floor board, the mechanical lockingsystem including a tongue on the first edge and a groove on the secondedge, the tongue and groove forming a first mechanical connectionlocking the first edge and the second edge to each other in a firstdirection at right angles to a principal plane of the floor boards, thetongue and the groove being formed in the material of the core layer,and a locking device arranged on an underside of the first edge and thesecond edge, the locking device forming a second mechanical connectionlocking the first edge and the second edge to each other in a seconddirection parallel to the principal plane and at right angles to theedges, wherein the locking device includes a locking groove whichextends parallel to and spaced from the second edge, the locking groovebeing open at the underside of the second edge and including an internalsurface, wherein the locking device further includes a strip extendingfrom the first edge, the strip extending throughout substantially anentire length of the first edge and being provided with a lockingelement projecting from the strip, wherein the strip, the lockingelement, and the locking groove are configured such that when the secondedge is pressed against an upper part of the first edge and is thenangled down, the locking element can enter the locking groove, andwherein the locking element has a locking surface which faces the firstedge and is configured so as to contact the internal surface of thelocking groove to prevent substantial separation of the joined first andsecond edges.
 16. The floor panel of claim 15, wherein the core layer ismade of particle board.
 17. The floor panel of claim 15, wherein theboard is equal to or less than 10 mm in thickness.
 18. The floor panelof claim 17, wherein the locking element has a locking surface with aheight of about 0.5 to 2 mm.
 19. The floor panel of claim 15, whereinthe core layer is made from particle board or other board material. 20.The floor panel of claim 15, wherein the locking element has a lockingsurface with a height of about 0.5 to 2 mm.